1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method of the same.
2. Description of the Related Art
What is called a chip size package (CSP) is known as a conventional semiconductor device, as described in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2008-218731. This semiconductor device comprises a semiconductor substrate. A wiring line is provided on the upper surface of an insulating film which is provided on the semiconductor substrate. An external connection electrode is provided on the upper surface of a land of the wiring line. A sealing film is provided on the upper surface of the insulating film including the wiring line around the external connection electrode. A solder bump is provided on the upper surface of the external connection electrode.
According to a method of manufacturing the above-mentioned conventional semiconductor device, after the wiring line and the external connection electrode are formed, the sealing film made of an epoxy resin is formed on the upper surface of the insulating film including the wiring line and the external connection electrode so that the thickness of the sealing film is slightly greater than the height of the external connection electrode. Therefore, in this condition, the upper surface of the external connection electrode is covered with the sealing film. The upper side of the sealing film and the upper part of the external connection electrode are then grounded to expose the upper surface of the external connection electrode. The solder bump is then formed on the exposed upper surface of the external connection electrode.
Although not described in Jpn. Pat. Appln. KOKAI Publication No. 2008-218731, a grind stone is used to grind (scrape off little by little) the upper side of the sealing film and the upper part of the external connection electrode. Therefore, burrs are generated in the upper surface of the external connection electrode which has been ground and thereby torn, and burrs are formed in the upper surface of the sealing film stretching from the upper surface of the external connection electrode to its peripheral part. Accordingly, in general, as an after-treatment, the burrs formed in the upper surface of the sealing film stretching from the upper surface of the external connection electrode to its peripheral part are often removed by wet etching using an etching solution based on sulphuric acid.
However, if the burrs formed in the upper surface of the sealing film stretching from the upper surface of the external connection electrode to its peripheral part are removed, unnecessary dents are formed in the upper surface of the sealing film around the external connection electrode accordingly. Moreover, the height of the external connection electrode is unnecessarily reduced by overetching, and the etching solution infiltrates into a space between the external connection electrode and the sealing film. As a result, the upper peripheral part of the external connection electrode is unnecessarily etched and thinned, which causes a problem of a decreased quality of close contact between the external connection electrode and the sealing film. According to an embedded wafer level package (EWLP) which is a technique that directly embeds a wafer level package (WLP) into a printed wiring board, an opening is provided in an upper insulating film on the external connection electrode after the WLP is embedded, and the external connection electrode is thereby electrically connected to an upper wiring line. However, as the external connection electrode is in contact with both the surrounding sealing film and the upper insulating film on the peripheral edge of the opening, there is also a problem of a decreased quality of close contact in the vicinity of the border between the layers.